TO REVIEW

SKELETAL STRUCTURE OF LARYNX

6 Cartilages: Cricoid ThyroidArytenoidCorniculateCuneiformEpiglottic

1 Bone:Hyoid

Basic Structure/Layers of Vocal Folds:EpitheliumLamina PropriaThyroarytenoid (Vocalis) Muscle

Cricoid Cartilage (Anterior)

Thyroid Cartilage (Anterior)

Arytenoid, Corniculate, and Cuneiform Cartilages

Epiglottic Cartilage (Anterior, then Sagittal)

Hyoid Bone (Anterior)

MOVING ON....

INTRINSIC LARYNGEAL MUSCLES: All Paired

Arytenoid MusclesInterarytenoids (transverse, oblique)

Thyroarytenoid MusclesCricoarytenoid Muscles (posterior, lateral)Cricothyroid Muscles

INTRINSIC LARYNGEAL MUSCLES: All innervated by recurrent laryngeal nerveExcept: Cricothyroids innervated by external

branch of superior laryngeal nerve

Intrinsic Muscles Anterior-Superior View Intrinsic Muscles Posterior-Superior View

INTRINSIC MUSCLES: OPENING & CLOSING THE FOLDS

INTRINSIC MUSCLES: CLOSERS/ADDUCTORS

Lateral Cricoarytenoids (LCA)Interarytenoids (IA)

TransverseOblique

INTRINSIC MUSCLES: OPENERS/ABDUCTORSPosterior Cricoarytenoids (PCA)

Pull the arytenoids laterally to open the glottis

INTRINSIC MUSCLES: LENGTHENING AND SHORTENING THE FOLDS

INTRINSIC MUSCLES: LENGTHENERS/THINNING

Pitch/Frequency of voiced sounds is largely controlled by varying the length of the vocal folds. As the folds are lengthened, their mass per unit length is reduced. Consequently, they vibrate faster when lengthened.

The vocal folds are attached to the thyroid cartilage at the front and the arytenoid cartilage at the back. The arytenoid cartilage, however, rides on the cricoid cartilage. So the length of the folds is mainly achieved by using the Cricothyroid (CT) Muscles, which rock the cricoid cartilage backward and upward, causing rotational movement of the thyroid cartilage (moving it slightly forward and tipping its front end downward). The cricothyroid muscles also pull the arytenoid cartilages slightly backwards, as they ride on the cricoid cartilage. These movements enabled by the cricothyroid muscles both lengthen and thin the vocal folds.

INTRINSIC MUSCLES: LENGTHENERS/THINNING

INTRINSIC MUSCLES: SHORTENERS/THICKENING

Shortening of the vocal folds occurs when the thyroarytenoid muscles (TA) contracts. When the thyroarytenoid muscles are not opposed by the thyrocricoid muscles (the lengtheners), they exert a shortening-thickening-laxing influence on the vocal fold cover tissues.

IMPORTANT TO REMEMBER:The Lengtheners/Shorteners and Openers/Closers all work in constant relationship to each other.

TO RECAP:

Openers/Abductors: PCACloser/Adductors: LCA & IALengtheners: CTShorteners: TA

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